Abstract: The present invention provides a chimney flue cap for a fireplace which can easily be installed on the top of new or existing chimney flues. The cap comprises a generally planar sheet of metal designed to fit over the opening in the top of the flue. The cap is mounted to the flue by a hinge means formed from two plates. The first plate is mounted on the cap with a portion extending past an edge thereof. The extending portion is divided into three parts, the outer two of which are bent downward to form a portion of the hinge. The center flange is bent upward and is connected to a spring which urges the cap towards the open position. A second plate is mounted on the side of the flue and has three outwardly projecting tabs. Two tabs are connected to the downwardly depending flanges to form the hinge and the third tab serves as an anchor for the spring which opens the cap.